This invention relates to pianos and deals more particularly with an improved piano construction using a novel string panel for supporting the strings and replacing the conventional cast iron string plate or frame, and associated strengthening structure, of prior pianos.
The many strings of a piano create large forces which have to be reacted by their supporting structure, and the provision of a suitable carrying structure capable of bearing these forces without undue bending or other yielding is a continual problem with piano manufacturers. More than one hundred years ago cast iron string plates or frames were introduced and these, in various different forms, have become virtually standard in the industry. These cast iron plates were a significant advance over earlier string supports but nevertheless are subject to a number of drawbacks. For one thing a cast iron plate is itself quite heavy and is usually combined with a heavy auxiliary wooden strengthening structure such as the conventional post and beam back of an upright piano or the conventional wooden beam truss of a grand piano, thereby making the complete piano very heavy and difficult to move.
Another disadvantage of cast iron plates is that the wooden strengthening structure with which they are associated is subject to change with temperature, moisture, age and other environmental conditions so that the forces imposed on the plate by the supporting structure are likely to change and cause warping, bending or twisting of the plate with consequent undesirable effects on the tuning of the strings and other factors.
Also, in the casting of cast iron plates some unpredictable and uncontrollable shrinkage of the metal invariably takes place so that it is difficult or impossible to directly cast into the plate notches, holes or other string locating features which are accurately located relative to one another or to some given reference. Thus, when using cast-in string locating features the strings of different plates may have slightly different locations from plate to plate so as to make it necessary when assembling a piano to individually adjust, by a time consuming manual procedure, parts of the action, particularly the hammers, to the associated string plate.
The general object of the invention is, therefore, to provide a piano construction which includes a means for supporting the strings whereby the strings are firmly and satisfactorily supported while nevertheless avoiding the above stated disadvantages of present cast iron string plates and which string supporting means also achieves other important advantages.
More particularly, it is an object of the invention to provide, in a piano, a string supporting panel which replaces the conventional cast iron string plate or frame and its associated strengthening structure and which string panel is highly resistant to bending, warping, twisting or other deflection under the string loads, is light in weight and is capable of being made at competitive cost.
A further object of the invention is to provide a string panel of the foregoing character in which the string locations are readily accurately determined and are accurately repeatable from panel to panel thereby possibly allowing the hammers or other parts of the action to be preset, if desired, prior to assembly of the action with the string panel.
Still another object of the invention is to provide a piano construction using a string panel of the foregoing character and wherein the construction of the piano is simplified by using the string panel as the main frame of the instrument with other major components of the piano being directly connected to the panel for support.
Still another object of the invention is to provide, in a piano, a string panel of the foregoing character having a truly planar surface which may be used as a reference surface from which measurements may readily be taken or tools supported to accurately locate or position other parts of the piano, as for example, for supporting a router or other tool used to adjust the heights of the bridges, after assembly of the panel with a soundboard, to obtain the desired amount of down-bearing pressure of the strings on the bridges.
A still further object of the invention is to provide a string panel of the foregoing character wherein structure performing the function of a conventional pin block or wrest plank is incorporated in and made an integral part of the string panel.
Another object of the invention is to provide a piano construction permitting, for a given general size of piano, the use of longer bass strings due to the elimination of braces and other obstructions presently found on or in association with most string plates.
A further object of the invention is to provide a piano construction allowing, for a given general size of piano, a larger soundboard than otherwise generally used.
Other objects and advantages of the invention will be disclosed by and evident from the following written description and accompanying drawings describing and illustrating preferred embodiments of the invention.